1. Field of the Invention
The present invention is directed to optimizing bandwidth and efficiency in an all-fiber network. Dynamic all-fiber optical networks utilize fast tunable lasers for single-hop optical routing over a uni-directional fiber ring. Access to the ring is provided by a media access controller (MAC), wherein each node has a dedicated wavelength, and the fiber can simultaneously carry a plurality of dedicated wavelengths. Each fiber therefore has a number of wavelengths which matches the number of nodes. The tuned outgoing wavelengths from each node are received by the correspondingly tuned receiver in the destination node. The tunable wavelength, therefore, is used on a per-packet basis to send the packet at the wavelength of the intended recipient node.
2. Description of the Related Art
Such prior art networks are referred to as synchronous and slotted networks, the fiber ring is essentially divided into a plurality of time slots, with the time slots rotating uni-directionally around the ring. In some cases, two rings can be used with each node transmitting the same data on each ring, but in opposite directions. Each node can transmit a packet only within the boundaries of a time slot. The length of the time slot is typically fixed. Scheduling of packets is typically performed through the scheduling of wavelengths and time slots. In order to avoid collisions in time slots, only one node can transmit on each wavelength. Once a time slot has a packet at a particular wavelength, no other node can transmit in that time slot at that wavelength thereby freeing the wavelengths at that time slot.
The MMR and the SRR works (By Marco Ajmone Marsan, Andrea Bianco, Emilio Leonardi, A. Morabito, and Fabio Neri) are dealing with a slotted all-optical multi-ring topology. The MAC algorithm presented in these works is based on carrier-sense ability of each node and a fairness algorithm to prevent nodes starvation. The carrier-sense feature gives the network the ability to adapt transmission resources according to the traffic. Thus the network bandwidth can be used more optimally. However, this approach has also a drawback that the algorithm lacks the ability to reserve bandwidth; consequently the network does not support constant bit-rate traffic. One version of this issue was being dealt in the SR3 algorithm developed by the same authors (“SR3: A Bandwidth-Reservation MAC Protocol for Multimedia Applications over All-Optical WDM Multi-Rings”, Marco Ajmone Marsan, Andrea Bianco, Emilio Leonardi, A. Morabito, Fabio Neri). The SR3 algorithm is also based on the carrier-sense idea with additional capability of reserving bandwidth between two nodes. The reserve bandwidth between from source node to a specific destination node can be up to 1/N of the bandwidth (N is the number of nodes). Although the SR3 supports reservation and thus supports constant bit-rate traffic, the reservation limitation, which increases as the number of the nodes increases, limits the bandwidth that can be allocated to constant bit-rate traffic. Furthermore the carrier-sense approach requires a fairness algorithm in order to avoid node starvations. The fairness algorithm base on the SAT token can cause large delays. The delays created by the fairness algorithm causes that a fairness-based networks cannot transport delay sensitive traffic, such as voice/video traffic. In order to improve the fairness algorithm and minimize the delays an improved fairness algorithm was proposed by I. Cidon, L. Georgiadis, R. Guerin, and Y. Shavitt (“Improved Fairness Algorithm for Rings with Spatial Reuse”).